JP2011008016A - Developing device, image-forming device, and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic developing device which maintains the quality of a printed image, with the elapse of time, and reduces the fixation of a developing sleeve due to friction between a developer and the developing sleeve itself.SOLUTION: The developing device includes a two-component developer containing a toner, which contains at least a binding resin, a colorant and wax, and a carrier; and a developer carrier which carries the developer on its surface, rotates, and feeds the toner to a latent image on the surface of a latent image carrier, at a position at which the developer carrier faces the latent image carrier, to develop the image. In this case, inequalities are satisfied which include: 22×Dv-70<Sm<22×Dv-50, 3×Dv-1.2<Ra<0.3×Dv-0.8, and 1.7×Dv-7.0<Rz<1.7×Dv-5.0, wherein Dv (μm) represents the volume average particle size of the toner, Sm (μm) represents the average interval between the concavities and convexities in the longitudinal direction of the developer carrier, Ra (μm) represents the arithmetic average roughness, and Rz (μm) represents the 10-point average roughness.

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device using an electrophotographic method, and more specifically, a developing device capable of maintaining print image quality over time and reducing fixing of a developing sleeve due to friction between a developer and a developing sleeve, and an image forming apparatus including the developing device And a process cartridge.

  Conventionally, in an image forming process using an electrophotographic method, an image forming apparatus that develops an electrostatic latent image on an image carrier using a two-component developer has been widely used. In this image forming apparatus, a two-component developer composed of toner and carrier is magnetically attracted to the surface of the developer carrying member to form a magnetic brush, and the toner in the magnetic brush is transferred to a latent image by a developing electric field. The image is developed. In general image forming apparatuses as well as image forming apparatuses using a two-component developer, an image is transferred onto transfer paper, the image on the transfer paper is heated and melted, and then the image is fixed by applying pressure to the image. Heat fixing is performed. The image forming substance is composed of powder such as black called toner, or powder such as magenta, cyan, and yellow.

  The power used when the fixing device that performs the heat fixing heats and melts the image occupies most of the power required for the image forming apparatus. In recent years, low power consumption of an image forming apparatus has been demanded from the viewpoint of energy saving. For this purpose, it is necessary to lower the temperature for melting the image to enable low-temperature fixing. Further, the market demands that the image quality can be as high as that of offset printing in both electrophotographic systems.

  In view of the above viewpoints, development of toner having a small particle diameter has been actively conducted in recent years. By reducing the particle size of the toner, the amount of heat required for fixing can be reduced as compared with the conventional case, so that low-temperature fixing can be realized. Further, by reducing the particle size, the number of particles per pixel increases and the dot shape becomes uniform, so that the image resolution is increased. This leads to higher image quality.

  However, the toner having a small particle diameter generally tends to have a strong adhesive force, and the toner gradually sticks to the developer carrying member (hereinafter sometimes referred to as “developing sleeve”) of the developing device, thereby inhibiting development. End up. This is called sleeve fixation. Sleeve fixation is likely to occur in the non-image area when the same document is printed continuously. The toner is pressed against the developing sleeve by an electric field that attracts toner from the non-image area to the developing sleeve, which develops. It is considered that the process proceeds to fusion in the process of being rubbed by the carrier many times on the sleeve. As the fixing of the sleeve progresses, the toner density adjustment is affected, and the image quality is degraded, for example, the image density is decreased.

  To adjust the toner density, generally, a reference toner pattern is formed on the latent image carrier, the density of the toner pattern is detected by a light-reflective photosensor, and the developing bias is set according to the detection result. A toner density control method for controlling toner supply and a toner concentration control method for controlling toner supply from the toner supply device to the developing device are used (see, for example, Patent Document 1).

  If the fixing of the sleeve is proceeding at the position where the reference toner pattern is formed, the effective developing voltage becomes higher by the amount of toner fixing than the actual voltage when forming the toner pattern, and the latent image carrier Since the adhesion amount of the toner pattern on the (photosensitive member) increases, the value of Vsp / Vsg becomes low. In this state, the toner replenishment amount tends to be smaller than the required amount. When the sleeve is further fixed, this tendency becomes conspicuous, causing a problem in density adjustment and causing problems such as a decrease in density. Further, the phenomenon in which the toner adhesion amount increases due to the fixing of the sleeve is remarkable from the start of image formation until the image is formed for one round of the developing sleeve, and there is a phenomenon in which one round of the developing sleeve is darkened from the leading edge of the image.

  As a countermeasure against the sticking of the sleeve, in the developing device of the electrophotographic image forming apparatus, a force that pulls the toner away from the developing sleeve by grounding the developer regulating member that regulates the toner thickness on the surface of the developing sleeve or applying a voltage. (See, for example, Patent Documents 2 and 3), and it is also possible to prevent the sleeve from sticking by changing the magnetic force in the developing sleeve or forming an irregular uneven pattern on the developing sleeve surface. It is also known (see, for example, Patent Document 4), and it is also known to define the ten-point average roughness Rz and the average interval Sm of unevenness as the surface characteristics of the developing sleeve (see, for example, Patent Document 5). ).

However, conventionally, in an image forming apparatus using this type of developing device, such as a copying machine or a laser printer, for example, sandblasting is applied to the developer carrying member (developing sleeve) in order to secure a pumping amount of the developer on the developer carrying member. A developer regulating member (doctor blade) is provided in order to perform the surface treatment as described above and to make the layer thickness of the developer uniform.
However, when the image forming operation is repeated, the developer is stressed between the image carrier (photosensitive member) and the developing sleeve, and between the developing sleeve and the doctor blade, and the toner is fixed to the developing sleeve by being melted and fixed by frictional heat or the like. This happens. If the toner adheres to the developing sleeve, an abnormal image such as a decrease in density and background stains is generated.
Further, it has been clarified that the characteristics of the surface of the developing sleeve, the toner particle size and the toner particle size distribution are greatly involved in the cause of the sticking of the sleeve. Further, once the sleeve sticking occurs, the surface of the developing sleeve is covered with toner, and the sticking tends to accelerate with time.

For example, in Patent Documents 2 and 3, toner that adheres weakly to the developing sleeve by grounding the developer regulating member or applying a voltage to form an electric field between the developer layer thickness regulating member and the developing sleeve. Is transferred to the developer layer thickness regulating member by this electric field to prevent sticking of the sleeve. However, with this method, the toner with low adhesion can be peeled off, but the toner with strong adhesion remains stuck to the sleeve and cannot be completely prevented.
For example, in Patent Document 4, the sticking of the sleeve is prevented by changing the magnetic force in the developing sleeve or forming an irregular uneven pattern on the surface of the developing sleeve. However, since this method has an irregular uneven pattern, there is a concern that fixing may be accelerated in combination with the physical properties of the toner.
For example, in Patent Document 5, as the surface characteristics of the developing sleeve, a ten-point average roughness Rz and an average interval Sm of irregularities are defined. However, this method ignores the presence of fine irregularities in the roughness curve and may not be sufficient because the influence of the toner particle size is not taken into consideration.
Further, for example, in Patent Document 2, as the surface characteristics of the developing sleeve, the ten-point average roughness Rz and the average interval Sm between the irregularities are defined by the carrier particle diameter. However, this method may be insufficient for the same reason as in Patent Document 5.

  Further, it has been proposed that the gap between the latent image carrier and the developing sleeve is set to be somewhat wide to prevent the toner from adhering to or being pressed against the surface of the developer carrier due to the electric field effect (for example, patents). Reference 6). However, this method can also weaken the adhesion of the toner to the developer carrying member, but does not completely prevent the toner from sticking.

  Further, these methods cannot completely prevent the sleeve from being fixed, and the above-described problems occur due to the sleeve fixing at the reference toner pattern forming position.

  An object of the present invention relates to a developing device using an electrophotographic system, and is to provide a developing device capable of maintaining print image quality over time and reducing fixing of a developing sleeve due to friction between a developer and a developing sleeve. Another object of the present invention is to provide an image forming apparatus and a process cartridge having such a developing device.

  As a result of intensive studies, the present inventors have developed a developing device, an image forming apparatus, and a process cartridge according to the present invention in order to solve the above-described problems, specifically, the techniques described in (1) to (6) below. Characteristic.

(1) A developer container containing a two-component developer containing at least a binder resin, a colorant, a toner containing a wax and a carrier, and a latent image carrier at an opening provided in the developer container. The developer in the developer container is supported on the surface and rotates to supply toner to the latent image on the surface of the latent image carrier at a location facing the latent image carrier. In a developing device comprising: a developer carrying member to be developed; and a developer carrying member that applies a carrying force to the developer along the axial direction of the developer carrying member and stirs the developer.
The volume average particle diameter Dv (μm) of the toner, the uneven average interval Sm (μm) in the longitudinal direction of the developer carrier, the arithmetic average roughness Ra (μm), and the 10-point average roughness Rz (μm) A developing device satisfying the relationship:
22 × Dv−70 <Sm <22 × Dv-50
3 × Dv−1.2 <Ra <0.3 × Dv−0.8
1.7 * Dv-7.0 <Rz <1.7 * Dv-5.0
(2) The developing device according to (1), wherein the toner has a volume average particle size of 8 μm or less.
(3) The peak height W of the characteristic spectrum of the wax and the binder resin measured by the ATR method (total reflection method) using FT-IR (Fourier transform infrared spectroscopy analyzer) of the toner. The development according to (1) or (2) above, wherein the peak ratio (W / R) indicated by using the characteristic spectral peak height R is 0.050 to 0.100. apparatus.
(4) a latent image carrier, electrostatic latent image forming means for forming an electrostatic latent image on the image carrier, developing means for developing the electrostatic latent image on the latent image carrier with toner, In an image forming apparatus comprising transfer means for transferring a toner image on a latent image carrier to a transfer body,
An image forming apparatus, wherein the developing means is the developing device according to any one of (1) to (3).
(5) An electrostatic latent image of a reference toner pattern is formed on the latent image carrier, the reference toner pattern is developed by the developer carrier, and the reflection density of the reference toner pattern is detected. The image forming apparatus according to (4), further comprising means for adjusting density according to an output value.
(6) A process cartridge that is detachably attached to the image forming apparatus main body, wherein at least the latent image carrier and the developing device according to any one of (1) to (3) are integrally provided. Process cartridge.

  According to the use of the developing device, the image forming apparatus, and the process cartridge using the electrophotographic system of the present invention, the volume average particle diameter Dv (μm) of the toner and the average unevenness interval Sm (in the longitudinal direction of the developer carrier) μm), arithmetic average roughness Ra (μm), and 10-point average roughness Rz (μm) are specified as shown in the above formula, so that the printing image quality with time and friction between the developer and the developing sleeve are affected. Development sleeve sticking can be reduced.

It is a figure which shows the grinding process which is a run-out precision process of a developing sleeve. It is a graph which shows the characteristic IR spectrum of wax. It is a graph which shows the characteristic IR spectrum of the polyester resin which is an amorphous resin. It is a schematic block diagram which shows an example of the process cartridge of this invention. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus of the present invention. FIG. 6 is a partially enlarged view of the image forming apparatus in FIG. 5.

As a result of intensive studies on reducing toner adhesion (sleeve adhesion) to the developing sleeve due to friction between the developer and the developer carrying member (developing sleeve), the present inventors have determined that at least a binder resin, a colorant, and a wax A developer container that contains a two-component developer containing a toner containing a carrier and a carrier, and an opening provided in the developer container so as to face a latent image carrier (photoconductor). A developer carrying member for carrying and developing the developer in the developer container on the surface, rotating the toner image onto the latent image on the surface of the latent image carrying member, and developing the toner image at a location facing the latent image carrying member. (Developing sleeve) and a developer conveying member that imparts a conveying force to the developer along the axial direction of the developer carrying member and stirs the developer, and a volume average particle diameter of the toner Dv (μm) and the length of the developer carrier Direction of the unevenness average distance Sm (μm), the arithmetic average roughness Ra ([mu] m) and 10-point average roughness Rz ([mu] m) was found to be able to solve the above problems by using a developing device that satisfies the relationship of the following equation.
22 × Dv−70 <Sm <22 × Dv-50
3 × Dv−1.2 <Ra <0.3 × Dv−0.8
1.7 * Dv-7.0 <Rz <1.7 * Dv-5.0

The present invention is described in further detail below.
As described above, in order to make full use of the small particle size toner without being fixed to the sleeve, the volume average particle size Dv of the toner, the uneven average interval Sm in the longitudinal direction of the developing sleeve, the arithmetic average roughness Ra, and the 10-point average roughness It was found that the relationship with Rz is important. Although the detailed mechanism is not known, the Sm, Ra, and Rz values of the developing sleeve satisfy the above formula in accordance with the toner particle size to be used, so that the toner can be prevented from being caught in the groove and the sticking of the sleeve can be avoided. it is conceivable that. When the values of Sm, Ra, and Rz are larger than the threshold value, the toner is caught in the groove of the developing sleeve, and the sleeve is fixed. On the other hand, when the values of Sm, Ra, and Rz are smaller than the threshold value, the developer is not sufficiently lifted up, resulting in a problem that a sufficient print density cannot be obtained.

  The developing sleeve is manufactured as follows, for example. First, aluminum is extruded hot to form a cylindrical shape. As the material of the developing sleeve, brass, stainless steel, conductive resin or the like can be used in addition to aluminum, but aluminum is often used from the viewpoint of cost and accuracy. Next, cylindrical aluminum is cold-drawn from the inner peripheral surface of the die having V-shaped convex portions formed on the inner peripheral surface, thereby forming V-shaped grooves extending in the axial direction on the outer periphery of the developing sleeve at equal intervals. Is done. Here, the inner diameter of the die may be slightly smaller than the outer diameter of the sleeve, and processing for increasing the deflection accuracy of the sleeve may be performed simultaneously with the processing of the groove. The number of sleeves is about 50 to 100. The groove may be formed at the time of hot extrusion production of aluminum.

  Next, the flange 652a is press-fitted and fixed to one side of the raw tube. Grinding is performed on the outer periphery of the developing sleeve in such a state. The state is shown in FIG. One holding portion 780 of the grinding apparatus holds the boss portion 651a, and the other holding portion 780 holds the end portion of the sleeve. The boss portion 651a is supported as a journal portion of the developing sleeve so as to be rotatable by a doctor blade (not shown), and is supported by a shaft of a magnet that is a journal portion of the developing roller. Therefore, by grinding with the boss portion 651a as a reference, high runout accuracy is maintained even when incorporated in the developing device. Then, the sleeve is rotated by rotating the holding portion 780. Then, the grindstone 710a is slid in the axial direction of the developing sleeve 650, and grinding is performed until the outer peripheral runout of the developing sleeve 650 becomes 20 μm or less. At the same time, the outer periphery of the boss portion 651a as the journal portion of the developing sleeve is also ground by another grindstone 710b to increase the deflection accuracy of the boss portion 651a as the journal portion of the developing sleeve. Thereby, the gap fluctuation between the doctor blade and the developing sleeve and the gap fluctuation between the latent image carrier and the developing sleeve can be suppressed.

In the present invention, the developer container of the developing device contains a two-component developer containing a carrier and toner containing at least a binder resin, a colorant, and wax. The mixing ratio of the toner and the carrier in the two-component developer is preferably 1 to 10 parts by mass of the toner with respect to 100 parts by mass of the carrier.
Since it is desirable to use a toner having a small particle diameter, the volume average particle diameter of the toner is preferably 8 μm or less, and more preferably 4 to 7 μm. Use of a toner having a volume average particle size exceeding 8 μm tends to lower the resolution of the obtained image.

  Further, in the present invention, the characteristic peak height W of the wax measured by the ATR method (total reflection method) using the toner FT-IR (Fourier Transform Infrared Spectrometer) and the binder resin. It is preferable that the peak ratio W / R shown by using the peak height R of the characteristic spectrum is 0.050 to 0.100. When the peak ratio is less than 0.050, sleeve fixation does not occur, but offset occurs during fixing. On the other hand, when the peak ratio is more than 0.100, the wax tends to adhere to the surface of the developing sleeve, and the fine toner is easily fixed to the sleeve by using this as a trigger.

The amount of surface wax is determined from the peak intensity ratio known from the ATR spectrum by the ATR method (total reflection method) using FT-IR. Since the ATR method requires a smooth surface, the toner is pressure-molded to create a smooth surface. At this time, pressure molding was performed by applying 1 t to 0.6 g of toner for 30 sec to obtain a pellet having a diameter of 20 mm. In the present invention, the characteristic spectrum of the wax of 2850 cm ⁻¹ is W (FIG. 2), and the characteristic spectrum of the binder resin (for example, in the case of a polyester resin, the peak height of 829 cm ⁻¹ (FIG. 3) is R. , W / R can be calculated as the peak intensity ratio, and the peak intensity ratio in the present invention is obtained by converting the spectrum into absorbance and using the peak height.

Any known wax can be used as the release agent for the toner in the present invention, and in particular, de-free fatty acid type carnauba wax, montan wax and oxidized rice wax can be used alone or in combination. The carnauba wax is preferably a microcrystalline one, having an acid value of 5 or less and a particle size of 1 μm or less when dispersed in a toner binder. The montan wax generally refers to a montan wax refined from a mineral, and like a carnauba wax, it is preferably a microcrystal and an acid value (mgKOH / g) of 5 to 14. The oxidized rice wax is obtained by air-oxidizing rice bran wax, and the acid value is preferably 10-30.
As other mold release agents, any conventionally known mold release agents such as solid silicone varnish, higher fatty acid higher alcohol, montan ester wax, and low molecular weight polypropylene wax can be mixed and used.
The usage-amount of these mold release agents is 1-20 mass% with respect to binder resin, Preferably it is 3-10 mass%.

  In the present invention, the binder resin used for the toner is preferably a polyester resin capable of achieving low-temperature fixing. The polyester resin is obtained by condensation polymerization of alcohol and carboxylic acid.

  Examples of the alcohol used include glycols such as ethylene glycol, diethylene glycol, triethylene glycol and propylene glycol, etherified bisphenols such as 1,4-bis (hydroxymethyl) cyclohexane and bisphenol A, and other divalent alcohols. Mention may be made of monomers and trihydric or higher polyhydric alcohol monomers.

  Examples of carboxylic acids include divalent organic acid monomers such as maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, and malonic acid, 1,2,4-benzenetricarboxylic acid, 1 , 2,5-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methylenecarboxy Mention may be made of trivalent or higher polyvalent carboxylic acid monomers such as propane and 1,2,7,8-octanetetracarboxylic acid. Here, the glass transition temperature Tg of the polyester resin is preferably 55 ° C. or higher, more preferably 60 ° C. or higher, from the viewpoint of heat preservation.

In the present invention, as the resin component in the toner, a resin other than the polyester resin can be used in combination as long as the performance of the toner is not impaired. Examples of usable resins in this case include the following, but are not limited thereto.
Polystyrene, chloropolystyrene, poly α-methylstyrene, styrene / chlorostyrene copolymer, styrene / propylene copolymer, styrene / butadiene copolymer, styrene / vinyl chloride copolymer, styrene / vinyl acetate copolymer, styrene / Maleic acid copolymer, styrene / acrylic acid ester copolymer (styrene / methyl acrylate copolymer, styrene / ethyl acrylate copolymer, styrene / butyl acrylate copolymer, styrene / octyl acrylate copolymer) Styrene / phenyl acrylate copolymer, etc.), styrene / methacrylic acid ester copolymer (styrene / methyl methacrylate copolymer, styrene / ethyl methacrylate copolymer, styrene / butyl methacrylate copolymer, styrene) / Phenyl methacrylate copolymer, etc.), styrene / Α-chloromethyl acrylate copolymer, styrene resin such as styrene / acrylonitrile / acrylate ester copolymer (homopolymer or copolymer containing styrene or styrene substitution product), vinyl chloride resin, styrene / acetic acid Vinyl copolymer, rosin-modified maleic acid resin, phenol resin, epoxy resin, polyethylene resin, polypropylene resin, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene / ethyl acrylate copolymer, xylene resin, polyvinyl butyral resin, etc. , Petroleum resin, hydrogenated petroleum resin, etc.

  These resins are not limited to single use but can be used in combination of two or more. Also, these production methods are not particularly limited, and any of bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization can be used.

  In the present invention, examples of the colorant used in the toner include carbon black, lamp black, iron black, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa Yellow G, rhodamine 6C lake, calco oil blue, chrome yellow, quinacridone, Any conventionally known dyes and pigments such as benzidine yellow, rose bengal and triallylmethane dyes can be used alone or as a mixture, and can be used as a black toner or a full color toner. The amount of these colorants to be used is usually 1 to 30% by mass, preferably 3 to 20% by mass, based on the binder resin.

A charge control agent may be used in the toner of the present invention as necessary. As the charge control agent, any conventionally known charge control agent such as a nigrosine dye, a metal complex dye, or a quaternary ammonium salt can be used. Specific examples of the charge control agent include Bontron (product numbers: S-31, S-32, S-34, S-36, S-37, S-39, S-40, S-44, E-81, E -82, E-84, E-86, E-88, A, 1-A, 2-A, 3-A) (manufactured by Orient Chemical Industry Co., Ltd.), Kaya Charge (product numbers: N-1, N- 2), Kaya Set Black (product number: T-2, 004) (above, Nippon Kayaku Co., Ltd.)), Eisenspiron Black (T-37, T-77, T-95, TRH, TNS-2) ( As mentioned above, Hodogaya Chemical Industry Co., Ltd.), FCA-1001-N, FCA-1001-NB, FCA-1001-NZ (manufactured by Fujikura Kasei Co., Ltd.) and the like can be mentioned. be able to. The amount of these charge control agents used is 0.1 to 10% by mass, preferably 1 to 5% by mass, based on the binder resin.
These charge control agents can be used by mixing with a zirconium-based compound.

In addition to the pulverization method, the toner is a polymerization method in which particles containing a binder resin, a colorant and a wax are formed in an aqueous medium, for example, any of suspension polymerization method, emulsion polymerization aggregation method, and dissolution suspension method Can also be manufactured.
As an apparatus for melt-kneading the toner for producing the pulverized toner, a batch-type two-roll, a Banbury mixer, a continuous twin-screw extruder, a continuous single-screw kneader, or the like is preferably used.
For pulverization, coarse pulverization can be performed using a hammer mill or a rotoplex, and a fine pulverizer using a jet stream or a mechanical pulverizer can be used. The obtained toner has a volume average particle diameter of 3 to 15 μm, preferably 8 μm or less.

  In the toner of the present invention, an external additive may be used as necessary. As the external additive, any conventionally known external additive such as silica, titanium oxide, silicon carbide, aluminum oxide, barium titanate or the like can be used alone or in combination. The amount of these external additives used is 0.1 to 5% by mass, preferably 0.5 to 2% by mass, based on the total mass of the toner.

In the external addition of the external additive to the toner base, the toner base and the external additive are mixed and stirred using a mixer, and the external additive is crushed and coated on the toner surface. At this time, it is important in terms of durability that external additives such as inorganic fine particles and resin fine particles are uniformly and firmly attached to the toner base.
As a mixing method, a method of adding external additives stepwise is effective in controlling the release rate. The desired release rate can be controlled by first adding and mixing the material that does not easily adhere to the toner base, and then mixing the material that easily adheres to the toner base.

The toner produced as described above preferably has a volume average particle size of 8 μm or less, more preferably 3 to 8 μm.
In general, it is said that the smaller the toner particle size, the more advantageous it is to obtain a high-resolution and high-quality image, but it is disadvantageous for transferability and cleaning properties. . Also in the present invention, when the volume average particle diameter is smaller than 3 μm, there is a problem that the toner is fused to the surface of the carrier of the developer during a long period of stirring in the developing device and the charging ability of the carrier is lowered.
On the other hand, when the volume average particle diameter of the toner is larger than 15 μm, it is difficult to obtain a high-resolution and high-quality image, and the fluctuation of the toner particle diameter often increases.

  The volume average particle diameter can be measured as follows.

<Volume average particle diameter of toner>
The volume average particle diameter (Dv) of the toner is measured with a particle size measuring device (“Multisizer III”, manufactured by Beckman Coulter, Inc.) with an aperture diameter of 100 μm and analyzed with analysis software (Beckman Coulter Multisizer 3 Version 3.51). went. Specifically, 0.5 ml of 10% surfactant (alkylbenzene sulfonate Neogen SC-A; manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) is added to a 100 ml beaker made of glass, 0.5 g of each toner is added, and the mixture is mixed with a micropartel. Then, 80 ml of ion exchange water was added. The obtained dispersion was subjected to dispersion treatment for 10 minutes with an ultrasonic disperser (W-113MK-II; manufactured by Honda Electronics Co., Ltd.). The dispersion was measured using the Multisizer III and Isoton III (manufactured by Beckman Coulter, Inc.) as the measurement solution. In the measurement, the toner sample dispersion was dropped so that the concentration indicated by the apparatus was 8 ± 2%. In this measurement method, it is important that the concentration is 8 ± 2% from the viewpoint of the reproducibility of the particle size. Within this concentration range, no error occurs in the particle size.

The carrier can be selected as appropriate, but a carrier having a core material and a resin layer covering the core material is preferable.
The material of the core material can be appropriately selected from known materials, and examples thereof include manganese-strontium-based materials and manganese-magnesium-based materials of 50 emu / g to 90 emu / g. In order to ensure the image density, it is preferable to use a highly magnetized material such as iron powder of 100 emu / g or more and magnetite of 75 to 120 emu / g. In addition, it is preferable to use a low-magnetization material such as 30-80 emu / g of copper-zinc system because it can reduce the impact of the developer in a spiked state on the photoconductor and is advantageous for high image quality. . These may be used alone or in combination of two or more.
The volume average particle diameter of the core material is preferably 10 μm to 150 μm, and more preferably 40 μm to 100 μm. When the volume average particle diameter is less than 10 μm, fine powder increases in the carrier, magnetization per particle may decrease and carrier scattering may occur, and when it exceeds 150 μm, the specific surface area decreases, Toner scattering may occur, and in the case of full color with many solid portions, reproduction of the solid portions may be deteriorated.

  As the resin layer for covering the core material, the material of the resin layer is not particularly limited and can be appropriately selected from known resins according to the purpose. For example, amino resin, polyvinyl resin, polystyrene Resins, halogenated olefin resins, polyester resins, polycarbonate resins, polyethylene, polyvinyl fluoride, polyvinylidene fluoride, polytrifluoroethylene, polyhexafluoropropylene, copolymers of vinylidene fluoride and acrylic monomers, fluorine Copolymer of vinylidene fluoride and vinyl fluoride, fluoroterpolymers such as terpolymers of tetrafluoroethylene, vinylidene fluoride and non-fluorinated monomers, silicone resins, etc. Can be used.

  The process cartridge of the present invention includes a latent image carrier on which an electrostatic latent image is formed, and a developing device that develops the electrostatic latent image formed on the latent image carrier using the developer of the present invention. It is supported at least integrally and is detachable from the main body of the image forming apparatus. It should be noted that the process cartridge of the present invention may further support other means appropriately selected as needed.

  FIG. 4 shows an example of the process cartridge of the present invention. The process cartridge includes a photoreceptor 10 and includes a charging device 20, an exposure device 30, a developing device 40, a cleaning device 60, and a transfer device 80. These members can be the same as those used in the image forming apparatus described later.

  The image forming apparatus of the present invention includes at least a photoconductor, a charging device, an exposure device, a developing device, and a transfer device, and other means appropriately selected as necessary, for example, a fixing device, a charge eliminating device, a cleaning device, You may further have a recycling apparatus, a control apparatus, etc.

  The material, shape, structure, size and the like of the photoreceptor are not particularly limited and can be appropriately selected from known ones, but the shape is preferably a drum shape. Examples of the photoconductor include inorganic photoconductors such as amorphous silicon and selenium, and organic photoconductors (OPC) such as polysilane and phthalopolymethine. Amorphous silicon photoconductors are preferable in terms of long life. .

  The charging device is not particularly limited and can be appropriately selected depending on the purpose. For example, a known contact charger including a conductive or semiconductive roll, brush, film, rubber blade, Examples thereof include a non-contact charger using corona discharge such as corotron and scorotron. The charging device is preferably arranged in contact or non-contact with the photoreceptor, and charges the surface of the photoreceptor by applying a DC voltage and an AC voltage in a superimposed manner. The charging device is a charging roller that is disposed in close proximity to the photoconductor via a gap tape, and charges the surface of the photoconductor by applying a DC voltage and an AC voltage superimposed on the charging roller. Those that do are preferred.

  The exposure apparatus is not particularly limited as long as it can image-wise expose the surface of the photoreceptor charged by the charging apparatus, and can be appropriately selected according to the purpose. Examples thereof include a rod lens array system, a laser optical system, and a liquid crystal shutter optical system. In addition, you may employ | adopt the light back system which performs imagewise exposure from the back surface side of a photoreceptor.

  Examples of the developing device include a developer sleeve that contains the two-component developer of the present invention and that has at least a developer sleeve that can contact or non-contact the developer to the electrostatic latent image. It is preferable to prepare for. The developing device may be either a single-color developing device or a multi-color developing device, and examples thereof include a stirrer that charges a developer by frictional stirring and a rotatable magnet roller. In the developing device, for example, the toner and the carrier are mixed and stirred, and the toner is charged by friction at that time, and held on the surface of the rotating magnet roller in a raised state, thereby forming a magnetic brush. Since the magnet roller is disposed in the vicinity of the photoconductor, a part of the toner constituting the magnetic brush formed on the surface of the magnet roller moves to the surface of the photoconductor by an electric attractive force. As a result, the electrostatic latent image is developed with toner, and a visible image is formed on the surface of the photoreceptor. Note that an alternating electric field is preferably applied when the toner is moved to the surface of the photoreceptor.

  The transfer device preferably has a primary transfer device that transfers a visible image onto an intermediate transfer member to form a composite transfer image, and a secondary transfer device that transfers the composite transfer image onto a transfer target. The transfer device (primary transfer device, secondary transfer device) preferably has at least a transfer device that peels and charges the visible image formed on the photosensitive member toward the transfer target. There may be one transfer device or two or more transfer devices. Examples of the transfer device include a corona transfer device using corona discharge, a transfer belt, a transfer roller, a pressure transfer roller, and an adhesive transfer device.

The intermediate transfer member is not particularly limited and can be appropriately selected from known transfer members according to the purpose. Examples thereof include a transfer belt.
The transfer target is not particularly limited and can be appropriately selected from known recording media (recording paper).

  The fixing device is not particularly limited and may be appropriately selected according to the purpose. However, a fixing device that is heat-pressed and fixed using a known fixing member is preferable. The fixing member is preferably in the form of a roller or a belt, and examples thereof include a combination of a heating roller and a pressure roller, and a combination of a heating roller, a pressure roller and an endless belt. At this time, it is preferable that heating temperature is 80-200 degreeC normally.

In the present invention, the fixing device includes a heating body having a heating element, a film in contact with the heating body, and a pressure member in pressure contact with the heating body through the film. It is possible to use means for heating and press-fixing by passing the transfer body on which the received image is formed.
Depending on the purpose, for example, a known optical fixing device may be used together with the fixing device or instead of the fixing device.

  The neutralization device is not particularly limited, and may be any one as long as it can apply a neutralization bias to the photosensitive member, and can be appropriately selected from known neutralization devices. Examples thereof include a neutralization lamp.

  The cleaning device is not particularly limited as long as it can remove the toner remaining on the photoreceptor, and can be appropriately selected from known cleaners. For example, a magnetic brush cleaner, an electrostatic brush cleaner, a magnetic roller A cleaner, a blade cleaner, a brush cleaner, a web cleaner, etc. are mentioned.

  The recycling device is a device that recycles the toner removed by the cleaning device to the developing device, and is not particularly limited, and includes, for example, a known conveyance unit.

  The control device is not particularly limited as long as the movement of each device can be controlled, and can be appropriately selected according to the purpose. Examples thereof include devices such as a sequencer and a computer.

  The image forming apparatus of the present invention forms an electrostatic latent image of a reference toner pattern on a photoreceptor, develops the reference toner pattern with a developing sleeve, detects the reflection density of the reference toner pattern, and detects the detected output value. Therefore, it is preferable to adjust the toner density. According to such an image forming apparatus, since the electrostatic latent image is always developed with an appropriate amount of toner, a high-quality image can be stably obtained over a long period of time.

To adjust the toner density, as described above, a reference toner pattern is formed on the latent image carrier, the toner pattern density is detected by a light-reflective photosensor, and toner is replenished according to the detection result. A toner density control system that controls toner replenishment from the apparatus to the developing unit is used.
In this toner density control method, among the output values of the light reflection type photosensor, the output of the light reflection type photosensor with respect to the toner pattern on the latent image carrier is Vsp, and the toner non-adhered portion (background portion) on the image carrier. If the output value of the light-reflective photosensor is Vsg, normally, toner replenishment control is performed so that Vsp / Vsg is constant. When the toner adhesion amount of the reference toner pattern decreases, Vsp / Vsg rises, and it is determined that the toner concentration of the developer in the developing device is low, and the toner replenishment is performed from the toner replenishing device to the developing device. Is kept constant. On the contrary, when Vsp / Vsg is low, it is determined that the toner density of the developer in the developing device is high, and toner replenishment is not performed.

  Further, the toner density can be adjusted by correcting the developing bias Vb and the charging bias Vr as the image output set values based on the pattern density output value Vsp.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, this invention is not limited to this. In the following, “part” means mass part, and “%” means mass%.

[Example 1]
<Production Example of Toner 1>
Polyester resin (A) 45 parts (weight average molecular weight: 5,000, Tg: 63 ° C., THF insoluble content: 0%,
(Softening point: 143 ° C., molecular weight peak: 4,200)
Polyester resin (B) 45 parts (weight average molecular weight: 5,800, Tg: 62 ° C., chloroform insoluble content: 20%,
(Softening point 99 ° C, molecular weight peak: 3,600)
Styrene / acrylic resin 15 parts (weight average molecular weight: 26,000, Tg: 66 ° C., chloroform insoluble content: 4%,
(Softening point: 143 ° C, molecular weight peak: 4,300)
・ Wax 5 parts (De-free fatty acid type carnauba wax)
Carbon black (# 44: manufactured by Mitsubishi Chemical Corporation) 10 parts Zirconia compound 1 1 part (zirconium salicylate)
The mixture having the above composition is sufficiently stirred and mixed in a Henschel mixer, heated and melted at a temperature of 130 to 140 ° C. for about 30 minutes with a roll mill, cooled to room temperature, and then the obtained kneaded product is pulverized with a jet mill and an air classifier. Classification was performed to obtain a toner base. The air pressure of the jet mill was set to 0.65 MPa, and the air volume at the classifier was set to 500 m ³ / h. To the obtained toner base, 0.5 wt% of hydrophobic silica having an average particle diameter of 20 nm and 0.5 wt% of titanium oxide having an average particle diameter of 15 nm were added and mixed to obtain [Toner 1]. The obtained [Toner 1] had a volume average particle diameter of 5.0 μm and W / R of 0.100.

<Carrier production>
-Silicone resin solution 132.2 parts [Solid content 23% by mass (SR2410: manufactured by Toray Dow Corning Silicone)]
Aminosilane 0.66 part [solid content 100% by mass (SH6020: manufactured by Toray Dow Corning Silicone)]
Conductive particles 31 parts [Substrate: alumina, surface treatment: lower layer = tin dioxide / upper layer = tin dioxide indium oxide, particle size: 0.35 μm, particle powder specific resistance: 3.5 Ω · cm]
-300 parts of toluene was dispersed with a homomixer for 10 minutes to obtain a silicone resin coating film forming solution.
Volume average particle size: 70 μm calcined ferrite powder is used as the core material, and the temperature inside the coater is 40 ° C. by a Spira coater (Okada Seiko Co., Ltd.) so that the coating film forming solution has a film thickness of 0.15 μm on the core material surface. And dried. The obtained carrier was fired in an electric furnace at 300 ° C. for 1 hour. After cooling, the ferrite powder bulk was crushed using a sieve having an opening of 125 μm to obtain [Carrier].

[Evaluation]
4% by mass of the toner 1 produced as described above and 96% by mass of the above-produced carrier are mixed, and the resulting two-component developer is used to form an image forming apparatus (manufactured by Ricoh Co., Ltd.). IPSiO SP6220) is printed, and evaluation images are printed at 50,000 sheets / day, initial and 100,000 sheets, respectively. As an evaluation condition of the evaluation machine, the linear velocity was set to 450 mm / sec.
The developing sleeves used had Sm, Ra and Rz of 40 μm, 0.3 μm and 1.5 μm, respectively.
The image evaluation was made by comparing the printed image after printing 100,000 sheets with the first printed image and visually judging using a sample. In the sleeve evaluation, the most severely stained part was measured with a Macbeth densitometer and judged from the density. The results are shown in Table 1.

<Image evaluation>
○: Same image quality as the first image.
×: Image quality is inferior to that of the first sheet.
<Sleeve evaluation>
○: Concentration is 1.0 or less ×: Concentration is 1.0 or more

[Example 2]
Evaluation was conducted in the same manner as in Example 1 except that the developing sleeves having Sm, Ra and Rz of 60 μm, 0.7 μm and 3.5 μm were used. The results are shown in Table 1.

Example 3
Evaluation was performed in the same manner as in Example 1 except that 4 parts of wax was used and W / R was 0.050. The results are shown in Table 1.

Example 4
Evaluation was performed in the same manner as in Example 1 except that 4 parts of wax was used, W / R was 0.050, and Sm, Ra and Rz of the developing sleeve were 60 μm, 0.7 μm and 3.5 μm, respectively. . The results are shown in Table 1.

Example 5
The air pressure of the jet mill at the time of toner pulverization is 0.65 MPa, the volume average particle diameter of the toner is 7.0 μm, and the developing sleeves have Sm, Ra and Rz of 84 μm, 0.9 μm and 4.9 μm, respectively. Evaluation was performed in the same manner as in Example 1 except that. The results are shown in Table 1.

Example 6
The air pressure of the jet mill at the time of toner pulverization is 0.65 MPa, the volume average particle diameter of the toner is 7.0 μm, and the development sleeve Sm, Ra and Rz are 104 μm, 1.3 μm and 6.9 μm, respectively. Evaluation was performed in the same manner as in Example 1 except that. The results are shown in Table 1.

Example 7
The wax is 4 parts, the W / R is 0.050, the air pressure of the jet mill at the time of toner pulverization is 0.65 MPa, the volume average particle diameter of the toner is 7.0 μm, and Sm, Ra and Rz of the developing sleeve Were evaluated in the same manner as in Example 1 except that 84 μm, 0.9 μm and 4.9 μm were used. The results are shown in Table 1.

Example 8
The wax is 4 parts, the W / R is 0.050, the air pressure of the jet mill at the time of toner pulverization is 0.65 MPa, the volume average particle diameter of the toner is 7.0 μm, and Sm, Ra and Rz of the developing sleeve Were evaluated in the same manner as in Example 1 except that 104 μm, 1.3 μm, and 6.9 μm were used. The results are shown in Table 1.

Comparative Example 1
The developing sleeve was evaluated in the same manner as in Example 1 except that Sm, Ra, and Rz were 38 μm, 0.2 μm, and 1.3 μm, respectively. The results are shown in Table 1.

[Comparative Example 2]
The developing sleeve was evaluated in the same manner as in Example 1 except that Sm, Ra, and Rz were 62 μm, 0.8 μm, and 3.7 μm, respectively. The results are shown in Table 1.

[Comparative Example 3]
The air pressure of the jet mill at the time of toner pulverization is 0.65 MPa, the volume average particle diameter of the toner is 7.0 μm, and the developing sleeves have Sm, Ra and Rz of 82 μm, 0.8 μm and 4.7 μm, respectively. Evaluation was performed in the same manner as in Example 1 except that. The results are shown in Table 1.

[Comparative Example 4]
The air pressure of the jet mill at the time of toner pulverization was 0.65 MPa, the volume average particle diameter of the toner was 7.0 μm, and the sleeves having Sm, Ra and Rz of 106 μm, 1.5 μm and 7.1 μm were used. Except for the above, evaluation was performed in the same manner as in Example 1. The results are shown in Table 1.

  As described in Table 1, according to the present invention, good image evaluation and sleeve evaluation can be obtained. This shows that the maintenance of the print image quality with time and the fixation of the developing sleeve due to the friction between the developer and the developing sleeve have been reduced.

(In Fig. 1)
650 Development sleeve 651a Boss portion 652a Flange 710a Grinding stone 710b Grinding stone 780 Holding portion (in FIGS. 4 to 6)
10, 10K, 10Y, 10M, 10C Photoconductors 14, 15, 16 Support roller 17 Cleaning device 18 Image forming unit 20 Charging device 22 Secondary transfer device 23 Support roller 24 Secondary transfer belt 25 Fixing device 26 Fixing belt 27 Pressure Roller 28 Reversing device 30 Exposure device 32 Contact glass 33 First traveling member 34 Second traveling member 35 Imaging lens 36 Reading sensor 40 Developing device 49 Registration roller 50 Intermediate transfer member 52 Separating roller 53 Manual feed path 54 Manual feed tray 55 Switching Claw 56 Ejection roller 57 Ejection tray 60 Cleaning device 61 Development device 62 Transfer charger 70 Eliminating device 80 Transfer roller 120 Image forming means 130 Document table 142 Paper feed roller 143 Paper bank 144 Paper feed cassette 145 Separation roller 14 6 Paper Feed Path 147 Transport Roller 148 Paper Feed Path 150 Copier Main Body 200 Paper Feed Table 300 Scanner 400 Automatic Document Feeder (ADF)

JP 2006-251384 A JP 2001-228706 A JP 2002-323797 A JP 2001-242711 A JP 2000-258992 A JP 2004-004209 A

Claims (6)

A developer container that contains a two-component developer containing at least a binder resin, a colorant, a toner containing wax, and a carrier, and an opening provided in the developer container that faces the latent image carrier. The developer in the developer container is carried on the surface and rotated, and the toner is supplied to the latent image on the surface of the latent image carrier and developed at a position facing the latent image carrier. A developing device comprising: a developer carrying member; and a developer carrying member that imparts a carrying force to the developer along the axial direction of the developer carrying member and stirs the developer.
The volume average particle diameter Dv (μm) of the toner, the uneven average interval Sm (μm) in the longitudinal direction of the developer carrier, the arithmetic average roughness Ra (μm), and the 10-point average roughness Rz (μm) A developing device satisfying the relationship:
22 × Dv−70 <Sm <22 × Dv-50
3 × Dv−1.2 <Ra <0.3 × Dv−0.8
1.7 * Dv-7.0 <Rz <1.7 * Dv-5.0   The developing device according to claim 1, wherein the toner has a volume average particle diameter of 8 μm or less.   Using the toner FT-IR (Fourier Transform Infrared Spectroscopy), measured by the ATR method (total reflection method), the characteristic peak height W of the wax and the characteristic of the binder resin 3. The developing device according to claim 1, wherein a peak ratio (W / R) indicated by using a peak height R of a simple spectrum is 0.050 to 0.100. A latent image carrier, an electrostatic latent image forming unit for forming an electrostatic latent image on the image carrier, a developing unit for developing the electrostatic latent image on the latent image carrier with toner, and the latent image carrier In an image forming apparatus comprising transfer means for transferring a toner image on a body to a transfer body,
An image forming apparatus, wherein the developing means is the developing device according to claim 1.   An electrostatic latent image of a reference toner pattern is formed on the latent image carrier, the reference toner pattern is developed by the developer carrier, the reflection density of the reference toner pattern is detected, and the detected output value 5. The image forming apparatus according to claim 4, further comprising means for adjusting density.   4. A process cartridge which is detachably attached to an image forming apparatus main body, wherein at least the latent image carrier and the developing device according to claim 1 are integrally provided.

Images